DEFIBRILLATION THRESHOLDS AND PERIOPERATIVE MORTALITY ASSOCIATED WITH ENDOCARDIAL AND EPICARDIAL DEFIBRILLATION LEAD SYSTEMS

Defibrillation thresholds (DFT) and perioperative mortality were evaluated in 123 patients who had endocardial defibrillation leads implanted in conjunction with the Medtronic model 7216A/7217 (Medtronic, Inc.) cardioverter-defibrillator (ICD). Clinical variables, implant DFTs, and 30-day perioperative mortality were compared with 266 patients who had the ICD implanted with epicardial defibrillation leads. The two groups were comparable in age, gender, and incidence of coronary artery disease. New York Heart Association Class I and II were more frequent in patients with endocardial leads (87.7%) as compared to those with epicardial leads (78.8%; P < 0.001). Mean left ventricular ejection fraction was significantly higher in patients with the endocardial lead system (37% vs 33%; P < 0.05). A significant proportion of patients with epicardial lead systems underwent another cardiac surgical procedure at the time of ICD implantation (13.9%) as compared to none in those who had endocardial leads implanted (P < 0.001). All patients with endocardial leads had implantation of triple lead systems as compared to 53.4% with epicardial leads (P < 0.001). The mean DFT at implant was lower in epicardial lead recipients (8.9 J) as compared to endocardial lead recipients (13.3 J; P < 0.001). Perioperative mortality had a significant trend to lower risk for endocardial lead systems (0.8%) as compared to epicardial systems (4.2%; P = 0.07). We conclude that this endocardial lead system has additional electrode and higher defibrillation energy requirements than the epicardial lead systems used with the Medtronic pacemaker ICD. However, the use of endocardial nonthoracotomy defibrillation leads is associated with a markedly reduced perioperative risk of ICD implantation. This could be due to patient characteristics, a less invasive implant procedure, and absence of concomitant cardiac surgery.